Chih-Chien Hsu

Antenna System Supporting Multiple Frequency Bands and Multiple Beams

A multiband antenna system supporting multiple communication services and multiple beams is presented. Key component of the antenna is the smooth-walled horn that has efficient radiation patterns over three frequency bands that are spread over an octave bandwidth and provides optimal illumination on the reflector at all the frequency bands. Results of the feed horn and the antenna are discussed.

Advanced antenna technologies for satellite communication payloads

A review of various antenna technologies suitable for satellite communications and applicable to fixed satellite, broadcast satellite, mobile communications, and personal communications services is presented. Antenna technologies suitable for generating contoured beam and multiple-beam antennas are reviewed. Design considerations for reflector antennas and feed assemblies and antenna performance in terms of coverage gain, sidelobe isolation, and cross-polar isolation are discussed. Current and future technological trends are presented in the above areas.

Low gain antenna performance impact due to spacecraft scattering

This paper presents impact of spacecraft scattering on the RF performance of low gain antennas used for communications satellites. The scattering analysis includes nadir deck structures, other spacecraft structures, large reflector used for high gain communication antennas, and solar panels. Impact of these spacecraft structures on both gain and cross-polar isolation of the low gain antennas is analyzed using ray-tracing analysis combined with physical optics (PO) integration of induced currents on these structures.

Common aperture satellite antenna system for multiple contoured beams and multiple spot beams

This paper presents a novel satellite antenna that generates simultaneously multiple contoured beams at Ku-band and multiple spot beams at Ka-band using a common aperture reflector antenna. It employs a shaped reflector that optimizes the RF performance of the desired Ku-band contoured beams on the ground by employing multiple corrugated horns that are located along the focal-plane of the reflector. The synthesized reflector surface at Ku-band is employed to generate the Ka-band spot beams by “un-folding” the large quadratic phase distribution using an optimized location for the Ka feeds that is far from the focal-plane and by placing the feeds on a spherical arc. The common aperture antenna replaces three or more large reflectors on the spacecraft and provides significant cost and mass reductions for future communications satellites.

Dual-Band Multiple Beam Antenna System Using Hybrid-Cell Reuse Scheme for Non-Uniform Satellite Communications Traffic

An advanced dual-band antenna system suitable for broadband satellites that is capable of providing higher EIRP, higher G/T, and improved copolar isolation among frequency reuse beams is presented. The antenna system employs a hybrid-cell frequency reuse scheme instead of conventional fixed cell reuse (4-cell or 7-cell) in order to efficiently use spectrum based on traffic demands. It is shown that the advanced antenna employing high-efficiency horns and shaped reflectors provides about 1.0 dB EIRP improvement, 2.0 dB G/T improvement, and 3.0 dB improvement in C/I when compared to conventional antennas.

Advanced multiple beam antenna system supporting multiple satellite communications services

This paper presents advanced antenna system suitable for multi-band communications satellites that could simultaneously support multiple services such as direct broadcast, Ka broadband and military communications. A multi-aperture reflector antenna system that could generate multiple spot beams simultaneously over five discrete frequency bands that are spread over more than an octave band is presented. A smooth-wall high efficiency multi-mode horn that operates over 12.3 GHz to 30.0 GHz has been developed. Results of the multi-beam antenna system supporting uplink and downlink frequencies for forward DBS, reverse DBS, and Ka broadband services are discussed.